[Ietf-languages] From Arabic to Latin

[Hugh Paterson III <[e-mail]>]

Greetings,

I am continuing my work with Latin text tagging. We have some cases where
texts are translations from other languages.

My understanding is that RFC6497 [1] adds a subtag -t to BCP-47. If I read
RFC6497 correctly, then [la-t-ar] would mean a Latin text transformed from
Arabic. My understanding is that RFC697 does not distinguish between
"transliteration, transcription, and translation". As I am dealing with
both ancient and modern texts one possible language tag for the first known
Latin translation of the Qur'an [into Medieval Latin by Robert of Ketton
(c. 1110 – 1160 AD)] *Lex Mahumet pseudoprophete* would be [la-t-ar]. (If
I'm not applying RFC697 correctly please comment!).

Now when applying language tags to modern contexts the website [
https://quran411.com/side-by-side-view?sn=1] provides the Qur'an in
Arabic Script on the right, an English Translation in the middle, and a
romanized transliteration on the left side. My understanding is that
RFC6497 would not necessarily be needed and the language content could be
accurately indicated in the following way:  [ar-Latn::en::ar]. However, if
I wanted to specify the type of transliteration method used I would need
to use [ar-t-ar-Latn]. But this tag seems to be missing something. How
would I construct a valid transliteration tag using the CLDR indication for
the Buckwalter method?

Questions:
1. How would I construct a valid transliteration tag from Arabic in
Arabic script  to Arabic in Latin Script using the CLDR indication for the
Buckwalter method?
2. When would it be appropriate to use [ar-t-ar-Latn] instead of just
[ar-Latn]? -- in my case I want to specify which transliteration system was
used.
3. What programmatic ways are there to determine if the -t- tag is used to
mean translation instead of just transliteration? Does just checking for
the same language tag on both sides of the -t- work for all use cases?
(e.g., sameLangage-t-sameLangage = transliteration :
sameLangage-t-differentLanguage = translation)
4. I am dealing with several different systems of transliteration within
bibliographic data (in library and archival contexts). For example,
Wikipedia outlines over 20 systems of transliterating Arabic script to
Latin script. Is there a way to designate the specific transliteration
method used? For example, I see Buckwalter Arabic transliteration system
mentioned in CLDR [5] but I don't see the Library of Congress'
transliteration table [6] or for that matter the BGN/PCGN 1956 System [7].

Kind Regards,
- Hugh Paterson III

[1]. https://www.ietf.org/rfc/rfc6497.txt
[2]. https://en.wikipedia.org/wiki/Lex_Mahumet_pseudoprophete
[3]. https://quran411.com/side-by-side-view?sn=1
[4]. https://en.wikipedia.org/wiki/Romanization_of_Arabic
[5].
https://github.com/unicode-org/cldr/blob/maint/maint-41/common/bcp47/transform.xml
[6]. https://www.loc.gov/catdir/cpso/romanization/arabic.pdf
[7].
https://assets.publishing.service.gov.uk/media/637df1aae90e076b73e074c7/ROMANIZATION_OF_ARABIC_-_Nov_22.pdf